1. Field of the Invention
This invention relates to improvements in digital circuits for remotely controlling the parameters of fully implantable heart pacers.
2. Description of the Prior Art
Recently, digital technology has been becoming of interest for use in heart pacers, as the cost of integrated circuit packages has dramatically decreased, and the number of available and reliable circuits has risen. An entirely digital heart pacer is shown, for example, by U.S. Pat. No. 3,557,796.
After the appearace of such digital circuits, heart pacer control circuits were advanced which enabled the parameters of the pacer to be remotely, non-invasively controlled. U.S. Pat. No. 3,805,796, for instance, provides a digital counter which counts the number of externally transmitted magnetic pulses. The counter controls bilateral switches which vary the biasing or currents of selected parameter controlling transistors.
In U.S. Pat. No. 3,833,005, a number of pulses are impressed upon an r-f signal transmitted to the implanted pacer where they are counted and stored in a counter for comparison with a repeating, resettable counter.
In none of the prior art circuits known to applicant, however, is the program or parameter controlling information directly sent or transmitted to the pacer. That is, in the prior art, the number of pulses sent is converted to a binary parameter controlling signal, rather than transmitting the binary controlling signal initially.